Question: Tiffany is 4 times as old as Michael and is also 18 years older than Michael. How old is Michael?
Solution: We can use the given information to write down two equations that describe the ages of Tiffany and Michael. Let Tiffany's current age be $t$ and Michael's current age be $m$ $t = 4m$ $t = m + 18$ Now we have two independent equations, and we can solve for our two unknowns. Since we are looking for $m$ , and both of our equations have $t$ alone on one side, this is a convenient time to use elimination. Subtracting the second equation from the first equation, we get: $0 =$ $4m$ $-$ $ (m + 18)$ which combines the information about $m$ from both of our original equations. Solving for $m$ , we get: $3 m = 18$ $m = 6$.